Page 1

Teac he r

ew i ev Pr

r o e t s Bo r e p ok u S

w ww

. te

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super


About Ready-Ed Publications Ready-Ed Publications was established in 1984 with the purpose of creating practical classroom blackline master activities. At the time, the role of the teacher was becoming ever more diverse with an increasing range of duties and responsibilities within the school and school community. Since then, the role of the teacher has continued to evolve with an escalating range of tasks and obligations, ensuring a reduction in time available to prepare work for the daily instructional program.

Ready-Ed

r o e t s Bo r e p ok u S

Throughout these past 24 years, Ready-Ed Publications has built a reputation as publishers of Australian made, high quality, innovative, timesaving materials for teachers of primary and lower secondary levels. In addition, all materials are based on state or national curriculum guidelines or specific age-related interest areas and subjects.

ew i ev Pr

Teac he r

Publications

Ready-Ed Publications aims to assist busy professionals by making available contemporary classroom materials that contain relevant and stimulating work to support the requirements of the curriculum. Bridges © 2009 Ready-Ed Publications Printed in Australia Author: David Holmsen

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y• Cover image: Clip art images have been obtained from Microsoft Design Gallery Live and are used under the terms of the End User License Agreement for Microsoft Word 2000. Please refer to www.microsoft.com/permission.

Acknowledgements I-stock Photos.

ii.

Clip art images have been obtained from Microsoft Design Gallery Live and are used under the terms of the End User License Agreement for Microsoft Word 2000. Please refer to www.microsoft.com/permission.

m . u

w ww

. te

i.

iii. Corel Corporation collection, 1600 Carling Ave., Ottawa, Ontario, Canada K1Z 8R7. iv. Wikimedia Commons. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.

o c . che e r o t r s super Published by:

Ready-Ed Publications PO Box 276 Greenwood WA 6024 www.readyed.com.au info@readyed.com.au

ISBN: 978 1 86397 775 3 COPYRIGHT NOTICE Permission is granted for the purchaser to photocopy sufficient copies for noncommercial educational purposes. However, this permission is not transferable and applies only to the purchasing individual or institution.

2


Contents r o e t s Bo r e p ok u S

Teac he r

6 7 8 9

Claim to Fame 1 Claim to Fame 2 Claim to Fame 3

10 11 12

How Bridges are Made Safe 1 How Bridges are Made Safe 2 How Bridges are Made Safe 3

26 27 28

Geronimo! 1 Geronimo! 2 Geronimo! 3

29 30 31

ew i ev Pr

Tell Me About Bridges 1 Tell Me About Bridges 2 Tell Me About Bridges 3 Tell Me About Bridges 4

Famous Bridge Mishaps and Collapses 1 32 Famous Bridge Mishaps and Collapses 2 33 Famous Bridge Mishaps and Collapses 3 34

© ReadyEdPubl i cat i ons The Four Bridge Designs 1 14 •f o rr vi ew15 puOpening r poas esonl y• 35 Bridge The Four Bridge Designs 2 e 13

Beam Bridge 1 Beam Bridge 2

w ww

The Arch Bridge 1 The Arch Bridge 2 The Arch Bridge 3

. te

16 17 18 19 20

It’s Opening Day

36

Bridges in Film Bridges in Film Bridges in Song Bridges in Tales and Rhymes

37 38 39 40

m . u

Stronger Bridges

o c . che e r o t r s super Bridge Activities

The Suspension Bridge 1 21 The Suspension Bridge 2 22 For the Teacher - Lessons in Suspension 23 The Cable-Stayed Bridge 1 The Cable-Stayed Bridge 2

Answers

41 47

24 25

3


Teachers’ Notes Bridges is written primarily for teachers of Design and Technology, but it can also be used in English and Information Technology lessons. It can be taught to Years 5, 6, 7 and 8, as the activities can be easily adapted to suit different age groups.

r o e t s Bo r e p ok u S

They are also encouraged to explore how bridges have played a main role in popular culture because they are so often viewed as strong symbols and metaphors. More bridge activities are provided at the back of the book and can be used for early finishers or to extend more able students.

ew i ev Pr

This book explores how engineers have, over time, planned, designed and constructed a range of bridges and learned from their mistakes and discoveries. It looks at the first and most recent bridges and examines the materials that have been tried and tested over the years. This book will help students appreciate why bridges stay up as well as understand why they sometimes tragically fall down.

Teac he r

Students are encouraged to test their own engineering skills by making their own bridges from a number of materials for a range of purposes.

© ReadyEdPubl i cat i ons Curriculum Links •f orr evi ew pur posesonl y•

w ww

• VIC (Design, Creativity and Technology) Investigating and Designing - Levels 4 & 5 Producing - Levels 4 & 5

. te

o c . che e r o t r s super

• ACT (Technology) ELA 25 - The student designs, makes and appraises using technology. 25.EA.1, 25.EA.5, 25.EA.8 • TAS (Vocational and Applied Learning) Innovation and Design – Standards 3 & 4 • NT (Design and Technology) Designing – Bands 3 & 4

4

• NSW (Design and Technology) Knowledge and understanding of design concepts and processes (1) Understanding and appreciation of the impact of past, current and emerging technologies on the individual, society and environment (2) Knowledge and understanding of skills in managing resources and producing quality design solutions. (6)

m . u

• WA (Technology and Enterprise) Materials (2) Enterprise (5) Technology Skills (6)

• SA (Design and Technology) Making – 3.5, 4.5

• Q/LAND (Technology) Technology Practice - Levels 4 & 5


Tell Me About Bridges 1 Listen to the Bridges

Deep valleys and vast water expanses are becoming worthy challenges for engineers who are now capable of building longer and bigger bridges than ever before.

r o e t s Bo r e p ok u S

There may come a time when no distance or object will be enough to stop the building of a bridge.

ew i ev Pr

Teac he r

The advancement of bridges has parallelled the advancement and spread of people around the globe. Bridges have helped millions of people every day go about their ordinary daily lives. Each bridge has a unique story to tell about the people whose lives are linked with its success or failure. Bridges tell the stories of the people who have designed, built and used them. They tell the stories of the people who have damaged and destroyed them. They tell the stories of the people who have then rebuilt, celebrated and strengthened them.

Bigger, Better Bridges

Bridges stand as proof of humankind’s incredible ingenuity.

Breaker! © ReadyEdRecord Pub l i cat i ons Research bridges that have broken world records. Look up •f orr ev i ew p u r po se s on l ythe • the longest bridge, the oldest bridge, the widest bridge,

Research 

w ww

The Longest Bridge: The Oldest Bridge:

. te

m . u

highest bridge, the most expensive bridge, the busiest bridge and the longest main span bridge. Record your findings below.

o c . che e r o t r s super

The Widest Bridge:

The Highest Bridge:

The Most Expensive Bridge: The Busiest Bridge:

The Longest Main Span Bridge:

5


Tell Me About Bridges 2 I Declare This A Bridge!

Bridges are in every place where people want to cross and are such a natural part of our every day life that we often take them for granted. They are born out of a necessity to achieve a more direct, efficient route. Generally, we think of bridges carrying people in cars as they hurry to work. However, they serve many other useful purposes, carrying such things as trains, trucks, buses, motorcyclists, pushbikes, pedestrians, power cables, water pipes, telephone cables and livestock. With continuing urbanisation, bridges are becoming increasingly important as governments seek ways to improve trade links, help us save time and minimise the costs of living.

ew i ev Pr

r o e t s Bo r e p ok u S

A bridge is a structure, either human-made or natural, that allows for transportation over a physical obstacle. Although bridges differ in the way that they look, they have many things in common. Typically, a bridge consists of a deck that is adequately supported for traffic to pass over. Bridges are readily recognisable because of this purpose, and if they achieve it, we can declare the object as a bridge.

Teac he r

What Exactly Do Bridges Do?

© ReadyEdP ubl i cat i ons Helpful Bridges Answer• thef questions below. orr evi ew pur posesonl y• Comprehension

1. How do bridges improve trade links? ________________________________________

m . u

________________________________________________________________________

w ww

2. How do bridges save us time? ______________________________________________ ________________________________________________________________________

. te

o c . che What If? e r o t r s super

3. How do bridges reduce the costs of living? ___________________________________ ________________________________________________________________________

Brainstorm 

What if an important bridge like the Sydney Harbour Bridge or the San Francisco Bridge (or a bridge in your city) was closed for a month? Suggest how people could still safely get from one place to another without the bridge. Have fun and include some more unusual ways – like an air balloon service. _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________

6


Tell Me About Bridges 3 How Do Bridges Work?

Lean On Me 1 Get organised into groups of three. Two members of the group should stand facing each other and grasp each other’s forearms, then gently lean back. The third member of the group should place a Tension book where the arms meet. The book represents a load on a bridge and will cause the arms to stretch a little further apart. This is tension.

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

A bridge can be as simple as a log or as sophisticated as the engineering marvel of the world’s highest road bridge over the Tarn Valley in France. For any bridge to work successfully, no matter what its size, it must be able to deal with two competing forces; compression and tension. Compression shortens the things it acts on, while tension acts in the opposite way; it expands the things it acts on. These forces appear every time someone or something (even wind or water) come in to contact with a bridge. The design of a bridge will try to spread or transfer these forces in different ways. If it is unable to do so, the forces will act to either break or weaken the bridge.

Group Activity

Lean On Me 2

To demonstrate compression, have two members of the group face each other again. This time they should place their palms together and Compression gently lean toward each other. The third member of the group should place a book where the arms meet. The book represents a load on a bridge and will cause the arms to push together a little. This is compression.

Compression

 

w ww

Tension

. te

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . My Silly Bridge Bridge toc Nowhere e her r o t s super

On the North Island in New Zealand there is a bridge in the Whanganui National Park that has been built with no roads leading to or from it! It has since become a popular tourist attraction.

Your Task 

Where do you think would be the silliest place to build a bridge? Scout your local area and find a place where you think a bridge would be a waste of time. Draw your bridge on a separate piece of paper and state its location and why it’s a silly place to have a bridge.

7


Tell Me About Bridges 4

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

Write a letter to the government stating your case for a new bridge to be built over a river in your city. Include drawings and diagrams to support your argument. Research the best type of bridge to be built and outline the benefits of the bridge to the local community. Present your argument to the class pretending that they are the government authorities. Use the space below to plan your letter.

w ww

. te

8

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super


when the very first humanmade bridge was built. Primitive men and women would have begun to use nature’s bridges before discovering a way to make bridges themselves. These would have been very simple bridges, made by placing slab stones over a stream or strategically moving fallen logs between river banks. The world’s first bridge engineer was the first person to rearranged a log or try to make a place sturdy enough to cross.

would have been mainly made from wood because there was lots of it and it is an easy material to work with. The Egyptians and Babylonians were known to be early bridge builders. The Chinese and Indians are thought to have built the earliest types of suspension bridges.

r o e t s Bo r e p ok u S

No single person can claim to have invented bridges. The very first bridges would have been naturally made from erosion or fallen trees or rocks forming overpasses. Said to be 500 millions years old, The Natural Bridge in Virginia USA is an example of a bridge formed from natural erosions.

Later, people would have learnt how to make bridges using combinations of materials such as placing branches end to end on stone piers. The first bridges

ew i ev Pr

Teac he r

Claim to Fame 1

The earliest recorded bridge ever built, was across the Euphrates River at Babylon around 784 BC. It was made from timber planks and with stone supporting columns and was held together by iron cramps. The planks were removed at night to stop criminals using the bridge.

© ReadyEdPubl i cat i ons It’s impossible to say exactly •f orr evi ew pur posesonl y•

w ww

In 480 BC, the Persian King Xerxes constructed a remarkable pontoon bridge made up of over 600 of his war ships tied together! It stretched 3.2 kilometres across the Hellespont in the Dardanelles. Unfortunately for the King, the bridge collapsed after a storm tore the ships apart. Enraged, the King ordered the waters of the Dardanelles to be whipped!

. te

Your Task 

Acrostic Poem

m . u

The Enraged King

Write an acrostic poem using the letters that spell the word bridges to tell the story of the enraged King. B

_________________________________________

o c . che e r o t r s super R

_________________________________________

I D

_________________________________________

G

_________________________________________

E

_________________________________________

S

_________________________________________

_________________________________________

9


Claim to Fame 2 It was the Romans though, who were the first to be recognised for their superior bridge building techniques and beautiful designs. The most famous of the Roman bridges is the Pons Sublicius. The Pons Sublicius was originally built from wood, “Pons Sublicius” Wikimedia commons before it was later rebuilt from stone. It was not unusual for early bridges to be destroyed and then rebuilt, sometimes many times. Over the course of 2000 years, London Bridge, for example, was built and re-built several times after being washed away, destroyed by invading Norwegians and levelled by fire.

r o e t s Bo r e p ok u S

Teac he r

ew i ev Pr

The Romans are most noted for their clever stone arch bridge designs, which they constructed all over their vast empire to help open up trade routes and move troops quickly. In 55 BC the Roman Emperor Julius Caesar built two famous bridges considered masterpieces of military engineering to help his 40,000 strong army cross the Rhine River. Historians claim that the strength of the Roman Empire during this time was largely due to the roads and the bridges that they constructed.

© ReadyEdPubl i cat i ons Comprehension  •f orr evi ew pur posesonl y• “London Bridge” Wikimedia commons

Reread the passage above and answer these questions.

1. Bridges often fell down in the early days of bridge building. Why?__________________

w ww

m . u

_________________________________________________________________________ 2. How did bridges help the Romans in times of war? ______________________________

. te

_________________________________________________________________________

Your Task 

o c . che e r o t r s super Think about Famous Bridges

Just about every city has bridges, but why do certain bridges become associated with cities, while other bridges go unnoticed? What bridges do you associate with the following cities: New York

_ ______________________

London

_ ______________________

San Francisco _ ______________________

Bath (UK)

_ ______________________

Sydney

Venice (Italy) _ ______________________

_ ______________________

Give one more example of a famous bridge and the city it is associated with:

10


Claim to Fame 3

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

Draw three different bridges – one that reflects the ancient past, one that reflects a bridge from today, and one that you think could represent a bridge of the future. Label and explain each of your three pictures. What is each bridge made from? What purpose does each bridge serve?

w ww

. te

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super

11


Stronger Bridges

Up until about 200 years ago, most bridges were still made from timber or stone and the stone masonry arch was very popular. However, things have changed. The first book written about bridges was by the French engineer Hubert Gautier in 1717. This was an important book because it documented a more analytical and calculated approach to bridge construction. The world’s first iron bridge was built over the Severn River in Telford in 1779, by Abraham Darby. This opened the way for engineers to build much stronger and larger bridges to carry heavy steam locomotive trains. During the 19th century, more stable bridges evolved, as new and better building materials became available. Increasingly, bridges became cheaper to build as iron reinforced concrete and low cost steel were used. Later, steel, as a cheaper, stronger material began replacing iron as the material of choice for bridge designers.

ew i ev Pr

r o e t s Bo r e p ok u S

“Iron Bridge” Wikimedia commons

Teac he r

By the 20th century four major types of bridges had emerged. They were: the beam bridge, the arch bridge, the suspension bridge and the cable-stayed bridge (the most recent design). Each type was developed over the course of human history from trial and error and from the environmental conditions which dictated to engineers what was possible. Improved technology and the refinement of building materials has enabled engineers to build bridges that were once impossible. Bridges have been built from almost every known substance: wood, stone, iron, steel, concrete and even “Steel wire rope” Wikimedia commons ice. Today, most bridges are built from combinations of steel and reinforced concrete. The future in bridge design is linked to what types of building materials are developed. New composite materials are being developed and some bridges are already made from special plastics. Bridges of the future will be environmentally friendlier, lighter, stronger and constructed from more durable and cheaper materials.

w ww

. te

Your Task 

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super Looking at Bridge Materials

List six materials that bridges can be built from.

Creative Challenge 

12

Draw some of the materials on a separate piece of paper.


The Four Bridge Designs 1 Every bridge is unique because no two bridges are built under exactly the same circumstances. They are all built in different places, in different times, using different materials, spanning different distances and they all serve different purposes.

Each of these bridge types can be described in more detail according to their type of span (e.g. continuous, cantilever, simple), the material that they are predominately made from (e.g. stone, concrete, steel) and where their road deck appears (e.g. deck, half-through, through). Sometimes bridges are a combination of bridge designs (hybrids) and cannot be identified as exclusively belonging to one particular category.

ew i ev Pr

The beam bridge The arch bridge The suspension bridge The cable-stayed bridge

Teac he r

As its name suggests, an arch bridge is identified by its arch shape. Built over short distances, these types of bridges are constantly under compression and so are constructed from materials strong enough to withstand pressure.

r o e t s Bo r e p ok u S

Engineers have developed bridges that fall into one of four basic categories: • • • •

The Arch Bridge

The Suspension Bridge

Suspension bridges © ReadyEdPubl i cat i o n s are strong and flexible and are •f orr evi ew pur poseso n l y designed to• be built

w ww

The beam bridge (also known as a girder) is the oldest, cheapest and most common of the bridge designs. It is also the most simple. A beam bridge is a horizontal platform placed over two end piers. The first beam bridges were just logs placed over streams. Early beam bridges were built from wood, but today they are typically made from reinforced concrete and steel that is needed to carry the weight of heavy trucks and trains.

. te

m . u

The Beam Bridge

over long distances. They have their disadvantages though. Read on.

The Cable-Stayed Bridge

o c . che e r o t r s super

Cable-stayed bridges are recognisable by their unique A, Y or diamond shaped towers. The towers are always in compression. Cable-stayed bridges are cheaper and easier to build than suspension bridges.

13


The Four Bridge Designs 2 Answer these Questions 1. In what order do you think the four bridges were invented? Explain your answer. _______________________________________________________________________

r o e t s Bo r e p ok u S

2. If you only had a tree trunk to use, which bridge design would you build?

_______________________________________________________________________

why.

ew i ev Pr

Teac he r

3. Which bridge do you think is better suited to be built over longer distances? Explain

_______________________________________________________________________ 4. Describe what an arch bridge looks like.

____________________________________________________________________

5. Which bridge do you think is the most popular bridge in the world? Explain your

© ReadyEdPubl i cat i ons 6. What are some materials bridges can be made from? • f o r r e v i e w p u r posesonl y• ____________________________________________________________________ answer.

____________________________________________________________________

w ww Extra 

m . u

_______________________________________________________________________

Test Your Skills

. Act teIt Out o Website Challenge c . che e r o t r s super

Use your body (no talking) to demonstrate the four different types of bridges – arch, beam, suspension and cable-stayed. Perform by yourself (or in a small group) in front of the class. You may use a limited number of props.

14

Log onto this website:

www.pbs.org/wgbh/nova/bridge/ and test your engineering skills. Match the right bridge to the right location.


Beam Bridge 1 How strong is the Beam Bridge?

To make beam bridges as strong as possible a supporting lattice construction called a truss can be added to the design, although this will only help to a point. As the beam distance increases, so must the size of the truss until the bridge will not be able to support the extra weight of the traffic and the truss itself. For this reason, a beam bridge span must be less than around 75 metres. If engineers need the bridge to cover a distance greater than this, they must use a technique called a continuous span. This is where a series of beam bridges are more or less joined together. This works successfully and in fact, the longest bridge in the world is a continuous span beam bridge; the Lake Pontchartrain Causeway in Louisiana (38.4 km).

r o e t s Bo r e p ok u S Compression

ew i ev Pr

Teac he r

When a car drives over a beam bridge, it causes the two edges of the beam to slightly push together. This is compression. In the meantime, the lower edges of the bridge become stretched. This is tension. The beam bridge works by moving the weight of the load vertically through the piers and to the ground. A beam bridge must be built strong enough to resist twisting and crumpling under the weight that it is carrying. The further apart the piers are built, the weaker the beam becomes. This is an inherent weakness of a beam bridge.

Strengthening the Beam Bridge

To increase the span size of beam bridges, a cantilever can also be used. The simplest way to understand the cantilever is to think of it as three separate spans joined together. Two spans are anchored and built from the shore towards each other – like diving platforms. These spans are joined together by a third span. Cantilever bridges are often supported (but not always) by trusses and the best known example of this design is Scotland’s Forth Bridge. Apart from a greater span capacity, cantilevers are useful when the terrain is difficult to build on, because they need little supporting structures (known as falsework), during their construction.

Your Task

Test It!

w ww

Create a beam bridge by supporting each end with a stack of books. Press down on the centre of the bridge. What happens? Keep adding weight to the middle of the beam. What eventually happens? Explain why.

. te

Make a List 

o c . che e r o t r s super The Good and The Bad

Reread the information about Beam Bridges. List the ADVANTAGES and DISADVANTAGES of these types of bridges on the back of this sheet.

Example of a cantilever in the ForthBridgeEdinburgh. Wikimedia commons

Tension

m . u

© ReadyEd ubl i cat i ons PierP supports ino supports •f rr evi ew pinur posesonl y• compression compression

Pier

15


Beam Bridge 2 comprehension 

Read page 16 and answer the questions below.

1. How do engineers make beam bridges as strong as possible?

r o e t s Bo r e p ok u S

_____________________________________________________________________

_____________________________________________________________________

2. Explain how beam bridges work.

ew i ev Pr

Teac he r

_____________________________________________________________________ _____________________________________________________________________

3. Beam bridges are more suited to shorter distances, but how can they be used for longer distances?

_____________________________________________________________________

© ReadyEdPubl i cat i ons _____________________________________________________________________ •f orr evi ew pur posesonl y• _____________________________________________________________________

4. How can engineers safely increase the span size of a beam bridge?_______________

Where to Build Beam Bridges

. te

m . u

w ww

Given what you know about beam bridges, where do you think they should be built? Draw pictures to illustrate the types of terrain and places where beam bridges should be built.

o c . che e r o t r s super

Create a Venn Diagram 

Cantilever and Beam Bridge

On a separate piece of paper, complete a Venn diagram which lists the similarities and differences between a cantilever and a beam bridge design.

16


The Arch Bridge 1 Arch diagram Arrows suggest forces acting on the structure

r o e t s Bo r e p ok u A S D

C

A - Abutments B - Voussoirs

B C

A

ew i ev Pr

Teac he r

Arch bridges are identified by a semicircular arch with supports (known as abutments) at each end. There are three basic variations to the way the arch appears. In a deck-arch, the road sits on top of the arch. These were very common from the times of Ancient Rome and are still popular today. In the half-through arch, the road is built through the middle of the arch. The third variation is the through-arch (or tied arch) bridge and has the road suspended from the arch. The through-arch design has the advantage of allowing boats to travel unheeded underneath. The Sydney Harbour Bridge, the Fort Pitt Bridge (USA) and the Tyne Bridge (UK) are examples of this type of bridge.

C - Footers D - Key Stone

© ReadyEdPubl i cat i ons • f o rr evi ew pur poseso n l y• Sydney Harbour Tyne Bridge Fort Pitt Bridge Bridge

Understanding the different types of arches

m . u

Your Task 

w ww

Find an example of a deck-arch and a half-through arch bridge. Draw and paste a picture of these types of arch bridges in the space below.

. te

Fort Pitt Bridge (Pittsburgh) Tyne Bridge (Newcastle) Sydney Harbour Bridge (Sydney)

o c . che e r o t r s super

17


The Arch Bridge 2 Arch bridges are most often used for shorter distances (60 to 240 metres), particularly where a centre pier is difficult to build, such as over deep valleys or freeways. It is the shape of the arch that gives the bridge its strength. Arch bridges work because the weight from the deck is distributed outward along the curve to the abutments at the bridge ends. This gives them a natural strength that allows them to be built without the need for additional supports or cables.

r o e t s Bo r e p ok u Test It! S

Demonstrate how arch bridges work. Cut out a 30 to 50 cm piece of firm cardboard. Make an arch shape from the cardboard and then gently place your hand or a weight on the arch centre. 1. What do you notice happens? _________________________________________ _________________________________________

  Research

ew i ev Pr

Teac he r

Group Activity 

Stone Arch Bridge

Building a Roman arch bridge requires a certain degree of skill and patience because during construction, the arch remains unstable until the last brick, called a keystone, is put in place.

© ReadyEdPubl i cat i ons Do some research then •f orr evi ew pur po• s e s o n l y • explain how to build a stone arch bridge.

. te

• Draw diagrams to support your explanation and clearly show the bridge building process.

m . u

w ww

Now place an even stack of books either end of the cardboard arch. Place your hand (or the weight) on the centre of the arch again.

o c . che e r o t r s super

2. What do you notice this time?

_________________________________________ _________________________________________

3. How does the stack of books affect the strength of the arch? _________________________________________ _________________________________________

Paying toll on a stone arch bridge, Wikimedia commons

18


The Arch Bridge 3

r o e t s Bo r e p ok u S

Comprehension 

ew i ev Pr

Teac he r

Arch bridges are always Sydney is an example of a under compression and modern arch bridge built so most modern arch from concrete. The Sydney Harbour Bridge is built bridges are made of steel from steel. The William or reinforced, prestressed concrete. Ancient Jolly Bridge in Brisbane is Roman engineers used made from a steel frame with a concrete veneer. stone to build their arch bridges. The Iron Bridge The oldest and longest known one-arch stone on the River Severn at Anji Bridge China, Wikimedia commons bridge in the world is the Coalbrookdale, England built in 1779 is made from cast iron. The Anji Bridge in China’s Hebei Province, built Gladesville Bridge on the Parramatta River in 1400 years ago in 605.

Answer the questions below.

1. How do arch bridges work? _____________________________________________________________________ _____________________________________________________________________

© ReadyEdPubl i cat i ons 3. Why do you think that so many people visit the Pont du Gard Bridge each year? •f orr evi ew pur posesonl y•

2. If you were to build an arch bridge today what materials might you use? _____________________________________________________________________

________________________________________________________________________ 4. Why do you think that the Anji bridge in China has lasted so long? ______________

w ww

m . u

________________________________________________________________________ 5. View the the next largest arch bridge ever built by logging on to this site: http:// hawtaction.com/2008/02/dubais-insane-new-bridge.html. On the back of this sheet, write a paragraph about what you see and write down two questions that you want to ask about the bridge.

. te

o c . che e r o t r s super

Pont Du Gard Aqueduct, Wikimedia commons

Research 

The arch bridge is one of the oldest and most successful designs. The most famous arch bridge in the world would have to be the World Heritage listed Pont du Gard aqueduct near Nîmes in France. It was built around 2000 years ago by the Romans to carry water across the Gardon River Valley. Incredibly, this three level 50 metre high stone bridge was constructed without mortar and held together by the force of its own weight. Pont du Gard is visited by over a million tourists every year.

Find out more about bridge aqueducts. What are they? Are they still being built today?

19


The Suspension Bridge 1

r o e t s Bo r e p ok u S

Some of the world’s most famous, longest and spectacular bridges are suspension designs. The Golden Gate Bridge and New York’s Brooklyn Bridge are two examples that you may know about. The world’s longest single span bridge is the Akashi Kaiyo Bridge in Japan.

The suspension bridge, however, did not start out in such a memorable way. It began as a simple rope that people used to swing over a chasm or river. Later, a deck made from wooden planks was added by securing it to suspended ropes. Suspension footbridges are quite common today and you may have even walked on one yourself.

ew i ev Pr

Teac he r

Like the name suggests, the deck of a suspension bridge is suspended from cables hanging from towers and secured at each end by anchorages. This allows the span to cover much greater distances than either a beam or arch bridge can. For this reason, you will see suspension bridges built over greater distances, particularly where central supports are too difficult or not practicable to build.

Photograph of Golden Gate Bridge by Rich Niewiroski Jr., Wikimedia Commons

Building Suspension Bridges cables under compression

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

. te

20

towers under compression

Deck

m . u

w ww

The father of the modern-day suspension bridge was American inventor James Finley. Finley built his famous Jacob’s Creek Bridge in 1801 to connect the towns of Uniontown and Greensburg in Pennsylvania. His innovative design secured the bridge with wrought iron chains fastened like anchors into the ground at each end. Further advancements came when iron chains were replaced with steel wire woven ropes. By using these stronger and more flexible cables, stronger and longer bridges could be built.

anchorages under tension

To build a suspension bridge, engineers begin with two strong towers. To keep the bridge balanced, steel cables are hung between them and secured to the ground in solid concrete blocks, called anchorages. The anchorages are positioned at each end of the bridge and absorb the tension in the main cables. Unlike arch and beam bridges, where the road rests on piers and abutments, suspension bridges hang the road from suspender cables (called hanger cables) attached to the main cables. Suspension bridges work by transferring weight to the towers and then to the ground.

o c . che e r o t r s super


The Suspension Bridge 2 Comprehension 

Answer the questions below.

r o e t s Bo r e p ok u S

1. How do suspension bridges work? ___________________________________ ___________________________________ 2. How would you help prevent suspension bridges from excessive swinging and swaying?

ew i ev Pr

Teac he r

Although suspension bridges are very strong and flexible, they are also susceptible to wind currents. Engineers have to take extra precautions to stabilise these type of bridges. The use of trusses make the decks sturdy and stop them from excessive swinging and swaying. This is what happened to the Tacoma Narrows Bridge just before it collapsed. To view this collapse go to www.youtube.com. Trusses are an effective way of strengthening bridges. Trusses are stiff framed triangular configurations.

___________________________________ ___________________________________ 3. Where are suspension bridges most likely to be built?

___________________________________

___________________________________ © ReadyEdP ubl i cat i ons Trusses •f orremain r ev epinnacle w puResearch  r poseson l y• Suspension bridges ati the Do some research and answer the questions below.

1. What are trusses made from? 2. Of these materials, what do you think is most commonly used on bridges today and why?

m . u

w ww

of engineer achievements. They are a testament to humans’ ability to build structures over almost impossible terrains and distances. The future of bridge design remains full of exciting possibilities, with suspension bridges at the forefront of designs.

. te List all the advantages and disadvantages of Make a List  o suspension bridges in the table below. c . che e r o r st super Advantages

Disadvantages

21


For the Teacher

Lessons in Suspension Classroom Activity

Make a Class Suspension Bridge

Make a Suspension Bridge

This exercise will demonstrate the value and need for anchorages in suspension designed bridges.

r o e t s Bo r e p ok u S

• You will need sixteen students to make the bridge, plus the remainder of the class to act as vehicles. • Four class members should hold a piece of rope parallel, about a metre or so apart and about a metre from the end. (The rope will act as the cables and the students holding the rope will be the towers.)

• Four students should sit on the floor, holding the very end of each rope. (This will be the anchorage.)

For this activity, you will need books of fairly equal size and weight and two pieces of string.

Stand two books upright and about 30 cm apart.

Connect the books by tying a piece of string around the top portion of the books.

Now put pressure on the cable by resting your finger at the centre of the rope construction.

ew i ev Pr

Teac he r

GrouP Activity

© ReadyEdPubl i cat i ons • Push down until the books •f orr evi ew pur p ose stheo nl y collapse. Note degree of •

• Ten students should kneel on the floor and gently grab the rope to act as the hanger cables. (The ground is the deck.)

• To explore how suspension bridges work, remove the anchorages and ask the students if the bridge still feels as strong.

. te

Rebuild the design, but this time, add anchorages by placing a stack of books at each end next to the upright books.

Tie the string around the upright books and secure it to the anchorages. Push down again until the books collapse.

m . u

w ww

• The remainder of the students can walk up and down the bridge as vehicles.

resistance.

o c . che e r o t r s super What do you notice this time?

22


The Cable-Stayed Bridge 1

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

A cable-stayed bridge can be thought of as the suspension bridge’s cousin. They both have their decks suspended from tall towers, making them a suspense structure. From a distance, the two bridges look similar, but there are some important differences. The suspension bridge has its deck hung from cables that are strung from tower to tower, whereas the cable-stayed road deck is suspended directly from cables hung from the tower itself. The cable-stayed bridge works by transferring the weight to the towers and then to the ground. The towers themselves are always in compression because the deck is pulled towards it. Engineers need to take precautions to ensure the deck doesn’t buckle. Most suspension bridges are typically built with two towers, but cable-stayed bridges can be built using one, two or more towers. The world’s tallest road bridge, the Viaduct de Millau, is built using seven towers.

The Rio-Antirrio bridge, Wikimedia Commons

A Popular Design

bridges have rapidly found © ReadyEdPCable-stayed ubl i c a t i obuilt ns acceptance and are now all around the world. In Australia, the ANZAC Bridge in Sydney and Melbourne’s Westgate •f orr evi ew pur p o s e s o n l y• Bridge are well known cable-stayed

. te

m . u

w ww

The cable-stayed bridge is considered a 20th century bridge, but its origin can be traced back to a famous book published in 1615 called the Machinae Novae where sketches of both suspension and cable-stayed bridges are clearly recognisable. Cable-stayed designs began showing up in the early 1800s but quickly faded after a number of collapses. The design did not really become popular until the construction of the Stromsund Bridge in Sweden in 1955. Engineers discovered that cable-stayed bridges were well-balanced, offered a more rigid design and didn’t require the large ground anchorages that suspension bridges needed.

bridges. The four towered 2.9 kilometre Rio-Antirio Bridge in Greece is considered a great engineering achievement. Cablestayed bridges are ideally, medium spanned bridges, but engineers are now designing long spanned cable-stays as well. Up until 2009, the world’s longest cable-stayed bridge was the Tatara Bridge in Japan, with a record span of 890 metres. It was eclipsed by 200 metres when China’s Sutong Bridge opened in 2009.

o c . che e r o t r s super

Cable-stayed bridges are an attractive and increasingly popular design. They have an aesthetic appeal and as they continue to push engineering boundaries, we will see a lot more of them around our cities and towns in the future.

23


The Cable-Stayed Bridge 2 Read about Cable-Stayed Bridges on page 24 and answer the questions below.

Your Task 

Comprehension 

You may want to work in pairs.

r o e t s Bo r e p ok u S Demonstrating a

1. What is the main similarity between a suspension and a cable-stayed bridge?

_______________________________________

Teac he r

_______________________________________ _______________________________________

_______________________________________ _______________________________________ _______________________________________

Cable-Stayed Bridge

This exercise will demonstrate how a cable-stayed bridge works.

• Tie a piece of rope at your elbows and position the rope over your head. Your elbows should be propped up like cablestays.

© R e a d y E d P u b l i c a t i o n s ____________________________________ •f orr evi ew pur po se so n l y ____________________________________ • Now stretch your arms out• and

____________________________________

4. What is the future of cable-stayed bridges? ______________________________________

w ww

______________________________________ ______________________________________

. te

______________________________________

Make a List 

tie another rope from wrist to wrist and run the rope over your head again. Where do you feel the pressure?

m . u

3. List three famous cable-stayed bridges.

• Your arms will now be horizontal and act as the road to carry the traffic (the load is transferred from your arms to your head).

o c . ch e List all the advantages and disadvantages of r e o cable-stayed int the table below. r s supbridges er

Advantages

24

ew i ev Pr

2. What is the main difference between a suspension and a cable-stayed bridge?

Disadvantages


How Bridges are Made Safe 1 Today, engineers use special computer designed software to help them build safe structures. The conditions of the area (e.g. the wind, soil or water) are carefully analysed and the proposed bridge design is tested for strength using computer simulations. Engineers also use models and devices like wind-tunnels to test bridge strength. For a number of decades now, engineers have been building bridges using a fail-safe design feature referred to as redundancy. The engineer designs the bridge to be so strong that if one element of the bridge fails, other elements can cover the weakness until it has been properly repaired.

r o e t s Bo r e p ok u S Inspecting Bridges

ew i ev Pr

Teac he r

Bridges have to be built to work properly. Noone is going to use bridges that are unstable or fall down all the time. To build a bridge that will carry cars, trucks and trains, requires technical expertise and know how. Civil engineers are people who study for many years to understand the laws of physics and material science that apply to bridge construction. They can design bridges and make them as safe as possible by taking into account the many things that can go wrong. Bridge designers can learn from the mistakes of the past, to develop better, safer designs for the future.

Once a bridge is built, it is continually examined by qualified bridge inspectors and structural and corrosion engineers. These experts are certified by the government and are required to keep updating their qualifications so that they can apply the latest technology and understandings to bridge inspections. Depending on the type and age of a bridge, it is usually inspected every one or two years.

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

. te

m . u

w ww

Bridge inspection involves carefully looking all over a bridge. Inspectors will walk over a bridge as well as under it. They have both high-tech and low-tech tools. Using a checklist, inspectors will look for things such as cracks, rust, general wear and tear and the condition of the bolts and rivets. Inspectors uses a ‘tap, look and listen’ technique that involves tapping a hammer against the metal and concrete to listen out for a hollow sound. A hollow sound indicates a crack or weakness. If inspectors suspect that something is wrong, they may have to use sophisticated equipment such as an ultrasound or X-ray to get a more accurate reading. After inspections, the inspectors write up reports that are compared with previous reports. Inspectors are looking for any signs of change in the bridge, big or small, that shows flaws or potential problems that need to be attended to.

o c . che e r o t r s super

If a bridge is deemed to be unsafe by inspectors, it is referred to as either ‘functionally obsolete’ or ‘structurally deficient’. A structurally deficient bridge means that the bridge can no longer carry the load it was originally designed for. Officials have the power to only let lighter vehicles use a structurally deficient bridge to reduce the risk of any further damage to the bridge or risk to the users. For example, as part of their regular maintenance, the inspectors of the Auckland Harbour Bridge in New Zealand discovered evidence of material fatigue. They have since restricted usage of the bridge. However, if a bridge is deemed functionally obsolete, inspectors believe that the bridge has a significant design problem and it is torn down and replaced.

25


How Bridges are Made Safe 2 Answer these Questions Read page 26 and answer the questions below. 1. Explain how redundancy could save people’s lives. _____________________________________________________________________

r o e t s Bo r e p ok u S

_____________________________________________________________________

2. What is the advantage of being able to test bridge designs in wind-tunnels and on the computer before they are built? _____________________________________________________________________

Teac he r

_____________________________________________________________________

ew i ev Pr

3. Why aren’t bridges normally inspected more often than once every one or two years?

_____________________________________________________________________

4. Do you think that it is a good idea to use trained and qualified bridge inspectors to examine bridges for safety? Explain your answer.

_____________________________________________________________________

_____________________________________________________________________

© ReadyEdPubl i cat i ons __________________________________________ •f orr evi ew pur posesonl y•

__________________________________________

__________________________________________

w ww Extra 

. te

Role Play

Make a List

m . u

5. Which bridge do you think is safer to cross - one that is declared ‘functionally obsolete’ or one that is declared ‘structurally deficient’?

o c . che e r o t r s super

Act out the role of a bridge inspector as he/ she walks up and down a bridge, tapping, looking and listening for flaws and weaknesses. Set it to music.

Bridge Safety Inspection Time

Bridge inspectors have a checklist of things that they need to look at. Below, list some important items that you think a bridge inspector might check in a typical routine inspection. •______________________________________________ •______________________________________________ •______________________________________________ •______________________________________________

26


How Bridges are Made Safe 3 Task 1 

What Would You Do?

Fact

r o e t s Bo r e p ok u S

Task  2

Fact

“A recent analysis of bridges in our city, shows that nearly 20% of Bright Light City bridges are structurally deficient and are showing signs of deterioration.” •

In pairs discuss what you would do next.

ew i ev Pr

Teac he r

If bridges are well designed and regularly maintained, they can last a very long time. Many of the Roman bridges built 2000 years ago are not only still standing, but are in perfect working order and are still being used today.

Imagine that you are the mayor of Bright Light City and that you have just been given a report that says,

What Shape is the Strongest? To test their strength against other shapes,

• Make a triangle, square and pentagonal shape from © Read y Edstrips Pu b l i ca t i ons cardboard held together with pins. • Gauge the strength of each shape by pushing the sides •f orr evi e w pur posesonl y• together. •

Record which shape offers the most resistance and why.

______________________________________________

w ww

______________________________________________

m . u

Triangles are the strongest geometrical shapes and are commonly used in bridge design and construction.

. te o Fact c . che e r o t r s super

Task 3 

As well as triangles, tubes are also remarkably strong. The Chinese built bridges from bamboo shoots because their shape made the bridges strong.

Test the Strength of aTube

In pairs discuss what other everyday items are constructed from tube shapes. To test the strength of a tube, •

Take two sheets of newspaper and make a bridge that will successfully hold up a book. (The secret to this challenge is to roll the paper into a tube shape.)

27


Geronimo! 1 Why Do Bridges Fall Down?

At the core of many bridge failures is the lack of proper care and attention to maintenance. Many bridges have needlessly fallen down because not enough due diligence was taken to look after them. In August 2007 the Minnesota Bridge collapsed into the Mississippi River during peak hour, killing 13 people. You can see this collapse at www.youtube.com. It was later revealed that problems with the Minnesota Bridge had surfaced ten years earlier when inspectors identified fatigue cracks and corrosion around the steel joints.

ew i ev Pr

r o e t s Bo r e p ok u S

Despite all the checks and careful planning, bridges still fall down. For a bridge to remain standing, it needs to withstand a combination of forces and pressures from things like: bending, tension, torsion, vibration, contraction, corrosion, erosion, expansion, fatigue, friction, rain, water flow, salt, temperature changes and wind turbulences. Even though a bridge may have even been designed to withstand these sorts of pressures, it can still fall down. How does this happen? Let’s look at the main reasons why.

Teac he r

Maintenance

w ww

. te

Minnesota Bridge collapse 2007, Wikimedia Commons

o c . che e r o t r s super

Tacoma Narrows Bridge collapse 1940, Wikimedia Commons

28

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

The Minnesota Bridge fell down because the load that it continually carried was too heavy and the connections between the bridge’s structural elements were too weak. Sometimes inspectors make mistakes or do not check bridges often enough to pick up a weakness in time. These terrible accidents serve as a constant reminder of the need for thorough and regular inspections.

Miscalculation

Bridges can fall down because the engineer misjudged or made a miscalculation that created a weakness in the design. Melbourne’s Westgate Bridge collapse is an example of what can go wrong when proper construction decisions are not made. However, it may not always be the engineer’s fault. The Tacoma Narrows Bridge collapse in 1940 was a result of the phenomenon called resonance, which was not properly understood until later.


Geronimo! 2 Excessive Force

Some bridges are too old or no longer suitable and are pulled down to make way for new and better designs. Sometimes bridges are sabotaged, when they become military targets during conflicts, to stop troop or supply movement. Throughout history, bridges have been attacked and fought over. Armies in Ancient Rome and armies today, have targeted bridges. In 2003 the US military deliberately bombed bridges throughout Baghdad during the Iraq invasion. The Israeli air force did the same when they invaded Lebanon in 2006. They bombed bridges surrounding Beirut in an attempt to seal off the city from the enemy.

ew i ev Pr

r o e t s Bo r e p ok u S

Extreme naturally occurring events like earthquakes, cyclonic winds, monsoons, heat, floods or freezing temperatures can damage bridges. A section of the San Francisco Bay Bridge double-decker span, collapsed during the Loma Prieta earthquake on October 17th, 1989. An even worse accident occurred in New Zealand in 1953 when a steam locomotive fell into the Whangaehu River after the bridge became damaged and weakened from lahar spewing from nearby Mount Ruapehu. Engineers have not yet been able to build bridges to withstand every natural force that the Earth experiences.

Teac he r

Bridges Fall Down On Purpose

© ReadyEdPubl i cat i ons •f o rr evi e w pur posesonl y• Bridge Misuse and Accidents

. te

m . u

w ww

Bridges are designed for a specific purpose and can come under serious pressure if they are not used in the way that they were intended to be used. Heavy trucks that cross bridges that are designed to carry only light cars, can cause structural damage. Accidents could cause weaknesses to bridges. This was the case when a barge collided with one of the piers on the I-40 Bridge in Okalahoma in 2002. This caused part of the span to collapse on top of the barge. A dozen cars and trucks plunged into the Arkansas River, tragically taking the lives of four people.

o c . che e r o t r s super

The Golden Gate Bridge in San Francisco is painted ‘international orange’ so that it is more visible to shipping during fogs. Australia’s worst bridge accident occurred in 1977, when a crowded commuter train travelling into Sydney derailed at Granville Station. It crashed into the supporting pillars of the Bold Street Bridge. The four lane overbridge then collapsed onto the train, killing 83 passengers and injuring 213.

29


Geronimo! 3 Interview an Eyewitness

Your Task

Imagine that you are a TV or a newspaper reporter interviewing an eyewitness to a bridge collapse. Create a list of interesting questions.

r o e t s Bo r e Time_______ Name of Bridge___________________ p o u k City________ Name of Eyewitness_______________ S

ew i ev Pr

Teac he r

Details of Bridge Collapse

Question 1_ _________________________________________________________ ___________________________________________________________________ qus on p37-38

Question 2_ _________________________________________________________ ___________________________________________________________________

© ReadyEdPubl i cat i ons ___________________________________________________________________ •f orr evi ew pur posesonl y• Question 3_ _________________________________________________________

Question 4_ _________________________________________________________

w ww

. te

Extra 

Read pages 29 and 30 and answer the questions below.

o c . che e r o t r s super

Cross in Safety

In small groups, come up with a way to get people across a dangerous, raging river. Explain what bridge design you have chosen and why. You may want to draw and label your final design.

30

Questions

m . u

___________________________________________________________________

1. What naturally occurring events can damage bridges? _____________________________________________ 2. List four other reasons why bridges weaken or are destroyed. _____________________________________________ _____________________________________________ _____________________________________________ _____________________________________________


Famous Bridge Mishaps and Collapses 1 Dangerous and Disruptive

Tacoma Narrows Bridge (USA)

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

Tacoma Narrows Bridge collapse is one of the world’s most famous bridge disasters, most When a bridge falls down, it’s usually news notably because it was actually worthy. Apart from being spectacular to filmed! In fact, you can see this witness and dangerous to the people on amazing footage on You Tube the bridge at the time, it can be extremely (www.youtube.com). So, what disruptive to people’s lives. In recent times, happened? The Tacoma Narrows the most famous bridge mishaps have been Bridge was built to link the city the ones in which video footage of them of Tacoma with Gig Harbor in collapsing has been available. Although any Washington State. Even before bridge collapsing is a very serious incident, it the bridge was finished, engineers can serve a useful purpose for engineers to noticed that when a breeze learn from mistakes in future construction blew, the road bridge rolled up and maintenance. and down. Even after making modifications, they were unable to fix the problem. The local residents nicknamed the bridge ‘Galloping Gertie’. Normally, you would expect that this would scare people away, but in fact, the opposite was true. The centre road span rolled and twisted and thousands of people flocked to experience the bridge ride of a lifetime. Although the authorities remained confident that the bridge was safe, on November 7th, 1940, just four months after opening, it collapsed. Before the bridge collapsed, the police became concerned about its increasing violent and constant motions and closed the bridge. An hour after it was closed, the bridge began to fall apart and then plunged into the Puget Sound waters below, where Your Task Describe the Last Moments it remains today. In 1950, a new Tacoma Narrows Bridge Have a look at the breathtaking footage of the was built in its place. The Tacoma Narrows Bridge collapse local residents named this bridge ‘Sturdy Gertie’. The www.youtube.com/watch?v=HxTZ446tbzE Tacoma Narrows Bridge collapse taught engineers Imagine that you are the last person on the bridge. an invaluable lesson about Describe this moment as you scramble to safety bridge aerodynamics, that before the bridge finally collapses. was not properly understood before.

w ww

. te

m . u

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super

31


Famous Bridge Mishaps and Collapses 2 Westgate Bridge (Australia)

Natural bridge collapse

r o e t s Bo r e p ok u S

Two years into construction, at precisely 11.50 am on 15th October 1970, a span between piers ten and eleven of the West Gate Bridge collapsed. Two thousand tonnes of steel and concrete crashed 50 metres into the Yarra below, taking with it the lives of 35 workers. Soon after, the government announced a Royal Commission into the accident. After eight months of investigation, the Commission concluded that the cause of the accident was a structural failure, brought on by the removal of bolts in an attempt to line up sections of the bridge. It was an accident that could well have been avoided but the lessons learnt from this disaster are taught to engineers today. The accident delayed the construction of the bridge by four years.

ew i ev Pr

Teac he r

The Westgate Bridge provides a link over the banks of the Yarra River between Melbourne’s sprawling western suburbs and downtown Melbourne. It stretches over two and a half kilometres, making it the third longest bridge in Australia. Completed in 1978 at a cost of $202 million, it now carries 190 0000 cars a day. As proud as Victorians are of this magnificent bridge, it also has a sad place in history; as the site of one of Australia's worst industrial accidents.

London Bridge on the Great Ocean Road in Victoria Wikimedia Commons

© ReadyEdInP ub l i ca t i on s 1990, a natural arch bridge collapsed. Known as the London Bridge, it could be seen along shoreline on the Great •f orr evi ew pu r p othese so n l y •

o c . che e r o t r s super

A memorial has been built at the bridge to remember the workers who were injured and lost their lives.

32

m . u

w ww

. te

Ocean Road in Victoria. At the time, two tourists were trapped on the second natural arch that remained. A helicopter was called to air-lift them to safety. Use the website below to help explain why the bridge collapsed. Present an oral report to a Safety Board recommending what to do with the bridge next to make it safe.

www.ga.gov.au/urban/factsheets/shore_ safety_arches.jsp


Famous Bridge Mishaps and Collapses 3 Millennium Bridge (England) The Millennium Bridge in London was opened on the 10th of June 2000. In a blaze of publicity, 160 000 people walked across the bridge on the opening weekend. It was the first new Thames crossing in more than 100 years and linked the City of London at St Paul's Cathedral with the new Tate Gallery at Bankside. At a cost of £18.2 million (approximately A$42 million), the 320 metre long suspension footbridge bridge design was considered an engineering innovation. It used a "lateral suspension" which meant that it could be built without the tall supporting columns that suspension bridges usually need.

r o e t s Bo r e p ok u S

Teac he r

ew i ev Pr

However, the bridge swayed badly and users complained of feeling sea-sick and had to steady themselves against the rails. The bridge was nicknamed the ‘Wobbly Bridge’ and just three days later it closed – causing much embarrassment to the engineers and City of London officials. Fortunately, no-one was hurt and most importantly, after an investigation, the engineers discovered the reason for the swaying. With 2000 people on the bridge at the same time, the small vibrations that each step generated, encouraged people to walk in step with each other. This caused the bridge to sway. It took another 18 months and £5 million (approximately A$12 million) worth of repairs and modifications before the Millennium Bridge was declared safe again and could re-open. Footbridges built today are safer, thanks to the lessons learnt from the ‘Wobbly Bridge’.

© ReadyE dPau bl i c at i o s Select Bridge Collapse orn Mishap of your Choice • f o r r e v i e w p ur posesonl y• There have been many, well documented bridge collapses. Select one to investigate

Your Task

w ww

A list of bridge collapses can be found on the wikipedia site at http://en.wikipedia.org/wiki/Listofbridgedisasters

m . u

further. Find out the reasons for the collapse (there are usually many contributing factors), the damage it caused and discuss the investigation into the collapse. You may wish to include diagrams and pictures.

. te o c Mishap and damaged caused: _________________________________________ . c e her r _________________________________________________________________ o t s super _________________________________________________________________

Bridge: _ ___________________________ Year of collapse/mishap____________ City_ _____________________________________________________________

Reasons for mishap:______________________________________

__________________________________________________ __________________________________________________ Include a diagram or picture with your report. 33


Opening a Bridge Opening of the Sydney HArbour Bridge

What if you were put in charge of organising a bridge opening?

r o e t s Bo r e p ok u Write up your proposal of ideas, S detailing what will happen and

Planner

List the people who you will invite. _________________________

There are many things to consider that require careful and thoughtful planning.

ew i ev Pr

Teac he r

On March 19th, 1932, nearly half of Sydney’s 1.2 million people attended the opening of the Harbour Bridge. The opening of a bridge is an exciting event. It attracts thousands of sightseers and well-wishers and is often covered widely by the media. Openings are in the papers the next day and on the news the same night.

Your Task

when in the planner below.

What activities will you have for them to do to join in the festivities?

© ReadyEd_________________________ Publ i cat i ons _________________________ •f orr evi ew pu r posesonl y• _________________________ _________________________ _________________________

w ww

Who will officially cut the ribbon to open the bridge?

. te

_________________________

_________________________

_________________________ Design a special commemorative token for this bridge opening. Choose from a coin, medal or postage stamp.

m . u

_________________________

o c . c e her r _________________________ o t s super _________________________ What media will you invite to be there to cover the event?

_________________________ How many people are you expecting? _________________________

34


It’s Opening Day You are a reporter for the opening day of a selected bridge. Write a recount of the day’s ceremonies and present your work in the form of a newspaper article. You may want to include a headline banner to make it look as authentic as possible.

r o e t s Bo r e p ok u S

ew i ev Pr

Teac he r

As a reporter, you will need to include such details as who, what, when and why. Include quotations from people at the opening and factual details about the bridge itself.

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________ © ReadyEdP ubl i cat i ons ___________________________________ ___________________________________ •f orr evi ew pur posesonl y• ___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

. te

m . u

___________________________________

w ww

___________________________________

o c . che e r o t r s super

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

35


Bridges in Film 1 Bridges in Popular culture

This film is based on a true story. During WWII, the Japanese captured many Americans, British and Australians and forced them to build a railway bridge over the river Kwai in the Burma-Thailand jungle. The railway bridge was to help the Japanese defeat the British, Americans and Australians. Essentially then, the prisoners were being forced to help their enemy win the war against their own countries. At first the prisoners did their best to sabotage the building of the bridge by working slowly and purposely making mistakes. However, the British officer in charge, Colonel Nicholson, reached an agreement with the Japanese commander to build the best bridge they could. The film climaxes when the British, Australian and American troops blow the bridge up, killing their own men. Bridge on the River Kwai was released in 1957 and won 7 Academy Awards, including Best Picture.

Write a Diary Entry

ew i ev Pr

r o e t s Bo r e p ok u S

Bridges often appear in popular culture. They are used as strong symbols and metaphors. There have been movies, documentaries, songs, nursery rhymes, stories and plays based around bridge themes.

Teac he r

Bridge on the River Kwai (Movie)

Choose fom the two points of view below

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y• 2. Write a diary entry from an Australian prisoner’s point of view. Think about the 1. Put yourself in the position of a Japanese solider. Write a diary entry detailing a typical day for you supervising the prisoners of war. Remember that your country expects you to force the prisoners to build the bridge.

m . u

conditions in which you have to work (long hours, humidity, poor diet). Think about the friends that you have lost, your family and friends at home and the reasons for and against sabotaging the building of the bridge.

w ww

_________________________________________________________________________ _________________________________________________________________________

. te

o c . che e r o t r s super

_________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 36


Bridges in Film 2 Write A plot

Write a plot outline for a movie based on a bridge theme. Use the headings below to help you with your outline.

Title: ______________________________________________________________

r o e t s Bo r e p ok u S

Main character: _ ____________________________________________________ Villain: _____________________________________________________________ Other characters: ___________________________________________________

ew i ev Pr

Teac he r

Setting: _ __________________________________________________________ __________________________________________________________________ Beginning: __________________________________________________________ __________________________________________________________________ __________________________________________________________________

© ReadyEdPubl i cat i ons __________________________________________________________________ •f orr evi ew pur posesonl y• Middle (complication and problem occurs):

__________________________________________________________________

m . u

__________________________________________________________________

w ww

__________________________________________________________________ Ending (resolution occurs – usually problem is solved):

. te

o c . che e r o t r s super

__________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Significance of bridge in movie: __________________________________________________________________ __________________________________________________________________

37


Bridges in Song Bridges are often used in songs because they are powerful symbols. There are many artists, who, over time, have used bridge themes in song. Bridge Over Troubled Water is a popular tune by the American singing duo Simon and Garfunkel. It was released in 1970 and became a number one hit song, winning 5 Grammy Awards, including Song Of The Year. Simon and Garfunkel also released another bridge title song called 59th Street Bridge Song. The Red Hot Chili Peppers had a hit with their most successful song, Under a Bridge.

r o e t s Bo r e p ok Bridge Over u Troubled Water S Questions

Teac he r

When you’re weary Feeling small When tears are in your eyes I will dry them all I’m on your side

ew i ev Pr

Read the first two verses of Bridge Over Troubled Water.

1. What does the bridge represent in this song?

________________________________________ ________________________________________ ________________________________________

2. List other popular tunes that have a bridge theme

orE title here. © Readyd Publ i cat i ons ________________________________________ •f orr evi ew pur posesonl y• ________________________________________

. te

Photocopy or write out the lyrics of one of the popular tunes that you have mentioned above. Look at the lyrics that you have written out again.

m . u

w ww

When times get rough And friends just can’t be found Like a bridge over troubled water I will lay me down Like a bridge over troubled water I will lay me down

3. What does the bridge represent in the lyrics?

________________________________________

o c . che e r o t r s super

________________________________________ ________________________________________

4. On the back of this sheet, write a two or three verse song about a bridge of your choice (e.g. Sydney Harbour Bridge). You might want to use an original song with your own lyrics or take an existing song and re-write it with your own lyrics. Try performing it as a rap tune to the class.

38


Bridges in Tales and Rhymes Three Billy Goats Gruff (Fairy Tale)

Your Task 

1. What does the bridge represent for the Billy Goats? ______________________________________________

r o e t s Bo r e p ok u S

______________________________________________ ______________________________________________ 2. What does the bridge represent for the Troll? ______________________________________________ ______________________________________________

ew i ev Pr

Teac he r

Three Billy Goats Gruff is a traditional fairy tale. It’s about three goats of different stature who need to cross a bridge in order to access greener pastures on the other side. However, they are stopped by a troll who lives under the bridge and threatens to eat them. Read the fairy tale at www.pitt. edu/~dash/type0122e.html and answer the questions.

______________________________________________ Activity: Act out Three Billy Goats Gruff. Re-write the setting and plot to put a more modern slant on it.

London Bridge is Falling Down

Your Task 

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

London Bridge is Falling Down is a catchy nursery rhyme tune. It describes some of the problems experienced during early attempts at building a bridge on the Thames River in London. Read through the lyrics. Write down what materials were used to build London bridge, what problems the builders experienced with each material and which material was used to finally construct the bridge.

London Bridge is falling down, falling down, falling down. London Bridge is falling down, my fair lady. How will we build it up, build it up, build it up? How will we build it up, my fair lady?

Problem:_____________________________

. te

Build it up with silver and gold, silver and gold, silver and gold. Build it up with silver and gold, my fair lady. Gold and silver I have none, I have none, I have none. Gold and silver I have none, my fair lady. Build it up with needles and pins, needles and pins, needles and pins. Build it up with needles and pins, my fair lady. Pins and needles bend and break, bend and break, bend and break. Pins and needles bend and break, my fair lady.

Build it up with wood and clay, wood and clay, wood and clay. Build it up with wood and clay, my fair lady. Wood and clay will wash away, wash away, wash away. Wood and clay will wash away, my fair lady.

m . u

Material:_ ____________________________

w ww

London Bridge is Falling Down

____________________________________

o c . che e r o t r s super Build it up with stone so strong, stone so strong, stone so strong. Build it up with stone so strong, my fair lady. Stone so strong will last so long, last so long, last so long. Stone so strong will last so long, my fair lady.

Material:_ ____________________________ Problem:_____________________________ ____________________________________ Material:_ ____________________________ Problem:_____________________________ ____________________________________ Material used to construct bridge: ____________________________________

39


Bridge Activities

Straw Bridge Challenge

In groups of three or four construct a straw bridge that will be tested for strength using coins or weights placed on the midpoint of the bridge.

Materials

r o e t s Bo r e p ok u S

20 drinking straws two stacks of wood or books coins or weights masking tape

The engineers on our team

• __________________ • __________________ • __________________ • __________________

4. The straws may be 1. The two ends of the span shortened, bent or cut. You must be made from two do not have to use all of stacks of wood or books them. and be placed 25cm apart. 5. When finished, place coins 2. The only materials that or weights on the bridge you may use for the bridge one at a time until the itself are 20 drinking straws beam collapses. and one metre of masking tape. 6. Complete a drawing of your group design on the 3. No part of the bridge may back of this sheet. touch anything between the two ends of the span. 7. Complete the post

ew i ev Pr

Teac he r

• • • •

Guidelines

construction review below.

© ReadyEdPubl i cat i ons •f orr ePost vi e w pur p osesonl y• Construction Review

w ww

 Beam

________________________________

 Suspension

. te

 Cable-stayed

________________________________

________________________________

6. What do you think makes a bridge strong or weak? (Look carefully to locate where the bridge gave way first.)

3. The length of the bridge

________________________________

________________________________

________________________________

4. The weight it supported before it collapsed was

7. How well did your group co-operate?

________________________________

________________________________

 Arch

o c . che e r o t r s super

2. Total height of the bridge

40

5. What worked well with your design and what didn’t?

m . u

1. What type of bridge does your design look most like?

________________________________


Bridge Activities

Lego Bridge Challenge

In groups of three or four design and construct a bridge that will successfully allow a golf ball to safely cross over it.

Guidelines

r o e t s Bo r e p ok u S Materials

• The bridge will need to cross a span of at least 30 cm.

The engineers on our team

• __________________ • __________________ • __________________ • __________________

• The golf ball must roll from one side to the other unheeded. The ball cannot be pushed across.

ew i ev Pr

Teac he r

• lego pieces • golf ball • pier

• The bridge should be mounted on piers set at least five cm above the surface of the desks.

• The only materials that you may use for the bridge are Lego pieces (or similar plastic bricks) provided.

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y• Post Construction Review

 Beam  Suspension

. te

5. What worked well with your design and what didn’t?

m . u

w ww

1. What type of bridge does your design look most like?

________________________________ ________________________________

o c . che e r o t r s super

 Cable-stayed

________________________________

6. What do you think makes a bridge strong or weak? (Look carefully to locate where the bridge gave way first.)

3. The length of the bridge

________________________________

________________________________

________________________________

4. The weight it supported before it collapsed was

7. How well did your group co-operate?

________________________________

________________________________

 Arch

2. Total height of the bridge

________________________________

41


Bridge Activities 1

Extra Classroom Ideas

Bridging Countries Engineers are now capable of building bridges further and higher than ever before. Make a case for building a bridge between two extended land masses such as:

r o e t s Bo r e p ok u S

•Mainland Australia and Tasmania •Africa and Europe •South Korea and Japan

•Australia and New Zealand •USA and Cuba •Sicily and Italy

Teac he r 2

Living Bridges

ew i ev Pr

Look at a world atlas to see where else you might one day want to construct a bridge. Examine the technical, political, social and economic challenges that such a project would face. Think about what the advantages and disadvantages of building such a bridge would be.

© ReadyEdPubl i cat i ons • f orr evi ew pur posesonl y• Find out more about living bridges and then design your own.

A living bridge is a bridge lined with buildings, such as shops and houses. The Ponte Vecchio in Florence (Italy), the Rialto Bridge in Venice (Italy) and the Pulteney Bridge in Bath (UK) are famous examples of living bridges. Although not many were ever built, the ones that have survived are now popular tourist sites. What purpose your living bridge has. Who you would allow to live or trade on the bridge.

3

w ww

You may also wish to make a scaled model of your design.

. te

m . u

Write about

o c . ch Compare Tunnels and Bridges e r er o t s super

Tunnels and bridges may serve a similar purpose, but they are different in their design. Bridges are structures that are built over or across physical obstacles, whereas tunnels are built under, or even through them. However, they both play an important role in moving people and goods around. Complete a Venn diagram to show the similarities and differences between tunnels and bridges.

42


Bridge Activities 4

Extra Classroom Ideas

Wacky Invention Invent your very own personal fold-away bridge that can fit on top of the roof of a car.

r o e t s Bo r e p ok u S

• Explain what its benefits are and the purpose of the bridge. • Draw and label your design.

5

ew i ev Pr

Teac he r

Extra: make a scaled model of your design.

Who Helps Make Bridges? civil helps design bridges. However, there many more ©Ainvolved Rengineer e ad yEd Pu bl i c aare t i on speople in making the idea of a bridge a reality. • r In groups, compile a list ofu allr the different people and organisations •f o r e v i e w p p o s e s o n l y• that you think are needed to plan and build a bridge. • Select one job that you would like to do and explain why you would like to do it.

6

m . u

w ww

• Create a table with the following headings on a separate piece of paper: People/Organisations, Job and Job I Would Like To Do and Why.

. te o c Sorting Out . che e r o t r s super In pairs:

• Collect as many pictures of bridges as you can. • Group the bridges into different categories and paste them on seperate pieces of paper. (Justify your decisions by observing such things as size, style, purpose, construction materials, shape and location of the bridges.)

43


Bridge Activities 7

Extra Classroom Ideas

Plan a trip • Plan a trip around the world visiting famous bridges. Which bridges would you like to visit and why?

Teac he r

• Make an itinerary of what you would like to see and do. Write down which is the best way to see each bridge.

1 8

ew i ev Pr

r o e t s Bo r e p ok u S

Write About Bridges You have been asked to write a book about bridges. What are the top 5 topics © ea E dCreate: Publ i cat i ons that youR would liked to y write about? • f orr evi ew pur posesonl y• A title for your book. Design a cover.

9

w ww

Include a blurb.

. te

o c . che e r o t r One Minute Speech s super Deliver a one minute passionate speech to the class entitled, ‘Bridges are one of humankind’s greatest inventions.’

44

m . u

Include a chapter list.


Bridge Activities 10

Extra Classroom Ideas

What’s in a Name?

11

r o e t s Bo r e p ok u S

• Collect some famous bridges and icons from around the world and have some fun renaming them using nicknames.

• Use pictures to explain your choice of names.

Buy a Bridge

ew i ev Pr

Teac he r

The Sydney Harbour Bridge was once popularly known as the ‘coat hanger’. The Tacoma Narrows Bridge was nicknamed ‘Galloping Gertie’ before it collapsed and was renamed ‘Sturdy Gertie’ when rebuilt.

©HeR e abridge dyEdP utransported bl i ca i o nsCity in had the disassembled and tot Lake Havasu Arizona where it was used as an attraction at an English theme park. •f oThe rMontrose r evi ewin Scotland pur panother ose so l y • Bridge was bridge thatn was dismantled

In 1968, the London Bridge was bought by American Robert P. McCulloch.

and then put up for sale on ebay.

w ww 12

m . u

• If you could buy any bridge in the world, which one would it be and why? • What would you do with the bridge after you had bought it?

. te o c Landmark Bridges . che e r o t r s super

Bridges frequently become attractive landmarks in towns or regions. • Which bridges do you think are most visually appealing? Why? • Use some well known bridges to illustrate your point. • Research and report your findings.

45


Answers Claim to Fame 2, page 11 Comprehension 1. In the early days of bridge building, engineers were still learning about which materials and designs were the best. Engineers began to get better through a ‘trial and error’ process. 2. The Romans were able to move their armies quickly around to the places that they were needed most. This proved to be an enormous tactical advantage over their enemies.

r o e t s Bo r e p ok u S

Your Task New York - Brooklyn Bridge San Francisco - Golden Gate Bridge Sydney - Sydney Harbour Bridge London - Tower Bridge Bath (UK) - Pulteney Bridge Venice (Italy) - Ponte di Rialto or The Bridge of Sighs

ew i ev Pr

Teac he r

Tell Me About Bridges 1, page 6 • The Longest Bridge: Lake Pontchartrain Causeway in Louisiana is 38.4 kilometres long and is listed in the Guinness Book of World Records as the longest bridge in the world. • The Oldest Bridge: Answers will vary as it is impossible to know who first laid a tree trunk across a stream or river. However some of the oldest bridges recorded are: • The Richmond Bridge in Tasmania built in 1823 and still in use today. • The Frankford Avenue Bridge built in 1697 is the oldest bridge in the United States and is still in use today. • The Tarr Steps in the Exmoor National Park, UK, is a prehistoric clapper bridge and dates back to around 1000 BC. • The Widest Bridge: The Sydney Harbour Bridge is the world’s widest long-span bridge. • The Highest Bridge: The highest deck-toground bridge in the world is the recently completed Siduhe Grand Bridge in China. It measures 649.83 metres above the ground. • The Most Expensive Bridge: Part of The San Francisco Oakland Bay Bridge was destroyed after the Loma Prieta earthquake in 1989. Repair work has commenced and is due to be completed in 2013. It will cost an estimated US $6.3 billion to repair. This makes it the most expensive bridge ever built. • The Busiest Bridge: According to their own website, The George Washington Bridge is the busiest bridge in the world, carrying nearly 100 million vehicles each year. However, if we consider pedestrians, the Howrah Bridge in India is even busier carrying 150,000 vehicles and 4,000,000 pedestrians a day. • The Longest Main Span Bridge: The longest main span bridge (point to a connection to another pier) is the Akashi Kaikyo Bridge in Japan, with a span of 1, 991 metres.

Stronger Bridges, page 13 Your Task Stone, concrete, steel, rope, wood, plastic, ice.

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super

Tell Me About Bridges 2, page 7 Comprehension 1. Bridges improve trade links by enabling a greater number of people to trade goods and services in a more efficient manner. 2. Bridges are built to overcome obstacles that add travel time between two places. 3. Bridges help reduce the costs of living by reducing the amount of fuel and time needed to transport goods and services. 46

m . u

w ww

. te

The Four Bridge Designs 2, page 15 1. Answers will vary, but the beam bridge was probably the first, followed by the suspension, then the arch and finally the cable-stayed bridge. 2. Answers will vary, but a beam bridge is an obvious answer because it is cheap, quick and easy to build. 3. Answers will vary, but suspension bridges have proven that they can be built over the longest distances. 4. An arch bridge is constructed in the form of an arch. 5. Answers will vary, but the beam bridge is possibly the most popular bridge because it is traditionally the cheapest and easiest to build. 6. Stone, concrete, steel, rope, wood, plastic, ice. Beam Bridge 1, page 16 Your Task When pressing down on the center of the bridge, the two edges of the beam push together, while the lower edges of the bridge become stretched. Adding too much weight will eventually cause the bridge to collapse because it is unable to resist the twisting and crimpling it’s causing. The length of a beam bridge is thus, limited by the weight of the beam itself and the weight that it carries.


Make a List Advantages • Cheap to build. • Simplest design. • Can be built in minimal time. • Disadvantages • Limited in length to less than 75 meters. • Don’t always easily allow traffic flow under the bridge.

The Arch Bridge 3, page 20 1. An arch bridge works by distributing the weight from the deck outward along the curve to the abutments at the bridge end. 2. Steel or reinforced pre-stressed concrete. 3. Answers will vary. It attracts many visitors because of its visual impact, age and the incredible building techniques used. 4. Answers will vary. The bridge has lasted because: it was well designed and constructed, it has been well looked after over the years and it is being used for its original purpose. 5. Answers will vary.

r o e t s Bo r e p ok u S

Where to Build Beam Bridges Beam bridges are usually built over shorter distances and over terrain that is easy to build over and provides easy access to cross. Students should also consider what the bridge will carry, e.g. people, cars, bikes and so forth.

ew i ev Pr

Teac he r

Beam Bridge 2, page 17 1. A supporting lattice construction called a truss can be added to the design. 2. Beam bridges work by shifting the weight from the vehicles traveling over them through to the supporting piers and to the ground. 3. Engineers use a technique called ‘continuous span’. This is more or less a series of beam bridges joined together. 4. Spans on beam bridges can be made longer using a cantilever.

meet at the top. Carefully remove the temporary bracing. The structure will remain unstable until it is completed.

Research Aqueducts are human-made open channels used to carry water. A bridge can be constructed to help carry the water over barriers such as rivers and lakes. Sometimes the bridges are built to not only carry water, but people as well. The Romans were most famous for building aqueducts, although the earlier Egyptians also used them. Water is now mostly carried in pipes buried under the ground. However, aqueducts are still being built and many of the Ancient Roman aqueducts are still used today. Aqueducts are used to not just supply water for drinking, but also for irrigating crops and to help control flooding.

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

. te

The Suspension Bridge 2, page 22 Comprehension 1. Suspension bridges work by transferring weight to the towers and then to the ground. 2. Adding trusses will help stabilise the bridge. 3. Suspension bridges are usually built over longer distances, especially in places where building central supports is too difficult or not practical – such as over rivers and deep crevices.

m . u

w ww

Create a Venn Diagram Similarities • The weight is carried vertically to the piers and abutments and then to the ground. • They can look similar. Differences • Beams on a cantilever bridge are anchored at each end, meeting in the middle. However, on a beam bridge, a single piece of material reaches from one side to the other. • Cantilevers have larger span sizes. • Cantilevers can also be supported by trusses.

o c . che e r o t r s super

The Arch Bridge 2, page 19 Test It! If the test is carried out correctly, students should notice that: 1. The arch will bend and quickly collapse. 2. The arch is more resistant to increased weight and more difficult to collapse. 3. The books act as abutments that prevent the ends of the arch from spreading apart.

Research How to build a stone arch bridge: begin by constructing a temporary scaffold that will be able to support the weight of the stones. Sit the stones on each other from both sides evenly until they

Make a List Advantages • They are strong and flexible. • Suspension bridges can be built over greater distances than other bridges. • They can be built high over valleys and waterways, allowing ships to pass unheeded. Disadvantages • They are susceptible to wind currents and may have to be closed, in strong winds. • Suspension bridges are costly to build.

47


Research 1. Wood, cast iron, wrought iron and structural steel. 2. Today trusses are made of structural steel as this is the strongest material. The Cable-Stayed Bridge 2, page 25 Your Task Students should feel the pressure shift from their arms (the bridge) to their heads (the towers).

Make a List Cracks, rust, general wear and tear, conditions of bolts and rivets. How Bridges are Made Safe, page 28 Task 2 The triangle will offer the most resistance because of its broad base and narrow top. Triangular shapes are commonly used to help make bridges stronger.

r o e t s Bo r e p ok u S

Make a List Advantages • Can be built with only one tower. • They are well balanced. • Aesthetically attractive bridges. • Require less ground anchorage. • They are usually cheaper to build than suspension bridges over the same span length. Disadvantages • Engineers need to take precautions to ensure that the decks do not buckle. • Generally suited more to shorter span distances than suspension bridges.

Geronimo! 3, page 31 1. Earthquakes, cyclonic winds, monsoons, heat, floods or freezing temperatures can damage bridges. 2. They can be destroyed or attacked on purpose, they have not been looked after or properly maintained, they have been built or designed incorrectly, a terrible accident has occurred, like a car accident and has caused a structural weakness.

ew i ev Pr

Comprehension 1. They both have decks suspended from towers, making them a suspension structure. 2. The decks on a suspension bridge hang from the cables strung between the towers, but the the decks on a cable-stayed bridge are hung from cables strung from the towers themselves. 3. Well known cable-stayed bridges include: ANZAC Bridge, Stromsund Bridge, Viaduct de Millau, Westgate Bridge, Rio-Antirio Bridge, Tatara Bridge and Sutong Bridge. 4. The future of cable-stayed bridges looks very promising. They are cost effective to build and have aesthetic appeal.

Teac he r

5. A structurally deficient bridge is safer because it can still be used, but not as it was originally designed. A structurally obsolete bridge must be torn down.

Bridges in Song, page 39 1. The bridge represents a means of helping a friend cross/overcome troubled times. The narrator compares helping his friend through rough times to the bridge helping someone to cross the troubled waters that lay beneath it.

© ReadyEdPubl i cat i ons •f orr evi ew pur posesonl y•

o c . che e r o t r s super

How Bridges are Made Safe 2, page 27 1. Redundancy can save lives because if one element of a bridge fails, it does not necessarily mean that the entire bridge will collapse. 2. Reduces the chance of errors in design and it’s less likely that people will get hurt in building or using the bridge. 3. It takes time for weakness to show. It may be a waste of time to inspect a bridge more often than is really needed. 4. Answer will vary. It can be considered a good idea because people’s lives and property are at immediate risk when a bridge is not properly cared for.

48

m . u

w ww

. te

Bridges in Tales and Rhymes, page 40 Three Billy Goats Gruff 1. For the Billy Goats, the bridge represents a passage to a place where the pastures are green and they can happily chew the grass. It also represents an obstacle or hindrance because they have trouble crossing the bridge. 2. The bridge, for the Troll, represents power. He uses it to assert his dominance over the goats. It also represents his downfall as he is thrown off the bridge. London Bridge is Falling Down Material: silver and gold Problem: too expensive Material: needles and pins Problem: not strong enough Material: wood and clay Problem: won’t resist water Material used to construct bridge: stone

Bridges  

This book explores how bridges can unite, link and help people. It also examines how bridges can barricade, obstruct and take people's lives...

Read more
Read more
Similar to
Popular now
Just for you